Electrical fuse



P. 1. SMITH.

- ELECTRICAL FUSE.

1,419,114. PatentedJune 6,1922.

- UNITED STATES PATENT, OFFICE.

PETER J. SMITH, OFCHICAGO, ILLINOIS, ASSIGNOR TO' COMMONWEALTH EDISONCOMPANY, OF CHICAGO, ILLINoISyA CORPORATION OF ILLINOIS.

ELECTRICAL EIISE.

Specification of Letters Patent.

Patented June 6,1922.

Application filed February 13,- 1919. Serial No. 276,741.

J. SMrrrna citi- 1 cago, in the county of Cook and State of Illinois,have invented a certain new and useful Improvement in Electrical Fuses,of which the following is a full, clear, concise, and exact description,reference being .had to the accompanying drawings, forming apart of thisspecification.

My invention relates to electrical fuses,

particularly such as are employed in fusible cutouts and the like.

Fusible cutouts are employed in practice to a great extent in primarycircuits of distributing systems for protecting the circuits againstoverload. Such cutouts generally comprise a socket member and a plugmem- -ber fitting thereinto. The socket member generally has stationarycontacts connected with the line and the plug member bears cooperatingcontacts connected by a fusible link. The particular form of the twomembers or the details of the cutout-is no part of my invention and I amexplaining the general character of the same only in order to make clearthe nature of the conditions under which a particular embodiment of myin? vention has proven to be highly successful.

Such cutouts are, generally mounted on poles or other exposed orsemi-exposed mountings and as such are subject to atmospheric influencesincluding moisture, acid and alkali fumes and the like.

The fusible link heretofore employed has consisted generally of analuminum ribbon connected between the contacts of the plug member.Considerable trouble has been experienced with corrosion of the fuseribbon,

apparently due to .an electrolytic action between the copperterminals-and the aluminum, which action may be explained as follows, 1

The aluminum and copper are'attacked by air with the impuritiescontained therein forming salts. on the surface of the metal. Thesesalts, exposed to moisture, form an electrolyte in the presence of whicha galvanicaction is set up, causing the more electropositive metal tobecome eaten away by electrolysis.

. Heretofore it has not been at all unusual tohave the'terminal portionsof the fuse eaten away by the corrosive action to such an extent as togreatly affect the-carrying capacity of the links. Such links cannot bemade of the same material as the terminals wlth any degree of successand aluminum heretofore has proven the most suitable metal for the link.

According to my invention the ends of the link are reinforced byemployin a double or multiple thickness of metal. referably this issecured in the ribbon type of fuse by folding the sheet material over toform a double thickness at each end of the ribbon for about two inchesin length to include the lug termmals. This insures the double advantageof compelling the fusible link to" blow at the proper point when it issubjected to overload, and it further prevents the corrosion o-fthe endsof the fuse from affecting the capacity of the fuse.

My invention will be more readily understood from the following detailspecification'and drawings:

Figure l isavertical axial .section of the well known form of fusiblecutout employmg a fuse of my invention;

Figure 2 is a plan view of a fuse embody i-ng my invention; and 1 Figure8 is a plan view of a blank before folding. w I The cutout shown inFigure 1 comprises the plug member 1' and the socket member 2.

The plug member 1 is.provided with a suita- -ble handle-3 whereby thesame may be withdrawn from the socket 2. The socket 2 is. supported bysuitable lag screws shown at 4 passin through a part of the socketmember. uitable terminals 5 are mounted withinthe socket member 2formaking connec-* tions with line wires which pass through thepetticoat of the socket member at the openin 6, I

Suitable stationary contact members connected to the terminals 5v areadapted to make contact .with the plug contact members 8.

The' plug contact leads are provided with suitable terminal portions 9,to which said terminalportions are fastend the ends 10 of the fusiblelinks 12. The fusible link is thus ut in. series with the line and isadapted to e blown and thus to sever the continuity ofthe line upon theoccurrence of overload conditions. The plug member 1 may be withdrawnfor renewing the fuse and may be inserted after the fuse has beenrenewed to close the line.

The fuse 12, which has clamping terminals portions 17 and 18 l0 and 11,is, formed of sheet metal having a single thickness along the centralportion as shown at 14, where the blowing of the fuse is adapted tooccur and it is provided with a double thickness of sheet metal alongthe end portions, including the clamping terminals10 and 11; The mannerof securing this double thickness is illustrated in Figure 3, whichshows the flange prior'to folding together the end of the fuse.

The blank shown in Figure '3 comprises the intermediate portion 14 whichis adapted to be blown by overload. This portion consists of a thinribbon-like strip of sheet aluminum. At portion, the terminal portion isformed in duplicate, adapted to be folded along the line 15 which is acontinuation of one edge portion 14. The folding' of the intermediateare folded on the lines 15 and 16 respectively to form a doublethickness of sheet metal at the terminal portions. I have shown the endportions as formed of greater width than the intermediate portions.

Vhile this is preferable, it is not essential. The formation of theclamping lugs 10 and 11 in the shape illustrated, may occur afterfolding as Well as before folding. This is a detail of manufacturewhichis immaterial.

The diagonal slots 19 and 20 extend away from the folded edge andprovide easy means for attaching the link to the terminals. The ends andslots are symmetrical so that either end may be attached first.

It is apparent that instead of a single fold at the end portions,further folds may be formed to increase the thickness if desired.

The fuse of-my invention is particularly form thickness such the ends ofthe intermediate" useful in cutouts, but I am aware that the inventionis applicable to fuses for any other type of apparatus. The fuse ispreferably made up of sheet metal of substantially unias is found in themarket at present, so that the construction ofthe fuse itself may beeasy and inexpensive.

I claim:

1. A flat sheet metal fuse having an intermediate portion and an endportion, the intermediate portion comprising a narrow flexible strip ofsingle thickness of sheet metal the end portion comprising pluralthicknemes of sheet metal integral with the intermediate portion, onethickness being a continuation longitudinally of the intermediateportion and the other thickness being a lateral continuation of saidfirst continuation and being folded over upon said first continuationalong a line running longitudinally of the fuse to produce an attachingterminal for the fuse.

2. A sheet metal fuse comprising a narrow flexible intermediate portionof a single thickness of sheet metal and end portions of greater widthand thickness said end portions being formed of integral extensions atthe ends of the intermediate portion folded flat together'insubstantially the same plane as the intermediate portion, the foldededge at each end being substantially in line with an edge of theintermediate portion said folded portions forming quick detachable lugsprojecting laterally from the edge remote from the folded edge; I

In witness whereof I hereunto subscribe my name this 11th day ofFebruary, 1919.

PETER J. SMITH.

